Power-feeding device

ABSTRACT

To minimize excessively high output or increases in magnetic-flux leakage by controlling power feeding on the power-feeding side if an unforeseen situation occurs. This power-feeding device ( 100 ) feeds power to an external power-receiving device ( 150 ) in a contactless manner. A power-feeding coil ( 103 ) uses electromagnetic power to feed electrical power to a power-receiving coil ( 154 ) in the power-receiving device ( 150 ). While power is being fed from said power-feeding coil ( 103 ), a power-feeding-side control unit ( 107 ) determines the amount of displacement of the power-feeding coil ( 103 ) and, on the basis of the determined displacement amount, controls the amount of electrical power being fed.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/778,425 filed Sep. 18, 2015, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present invention relates to a power supply apparatus that suppliespower to an external power receiving section using an electromagneticforce in a wireless manner.

BACKGROUND ART

Conventionally, wireless power supply systems have been known in whichpower is supplied while a power supply coil and a power receiving coilare placed facing each other in a wireless manner. In such wirelesspower supply systems, when vibration is added to the power supply sideduring power supply due to an earthquake or the like, the position ofthe power supply coil changes.

For example, in a wireless power supply system that supplies power to apower storage apparatus mounted on a vehicle such as an electricvehicle, a power supply apparatus is installed on the ground. In thiscase, when an earthquake occurs or when a large vehicle passes by,vibration occurs in the power supply apparatus and the position of thepower supply coil changes. When a wireless power supply system to supplypower to a portable device is mounted on a mobile unit such as avehicle, vibration occurs and the position of the power supply coilchanges as the mobile unit moves.

When the position of the power supply coil changes during power supply,coupling between the power supply coil and the power receiving coilchanges, causing excessive output or an increase in magnetic fluxleakage.

Conventionally, wireless power supply systems configured to stop acharging section mounted on the vehicle when an unexpected situationsuch as an earthquake occurs have been known (e.g., FIG. 10 in PatentLiterature (hereinafter, referred to as “PTL”) 1). When an unexpectedsituation occurs, the wireless power supply system of PTL 1 performscontrol of stopping power supply to a power storage apparatus by ECU.When resumption of the power supply is impossible, the power receivingside notifies the power supply side through communication that the powersupply stops. Thus, the technique in PTL 1 can reduce excessive outputor an increase in magnetic flux leakage associated with a change in thecoupling between the power supply coil and the power receiving coil.

CITATION LIST Patent Literature

-   PTL 1-   WO 2010/137145

SUMMARY OF INVENTION Technical Problem

However, according to PTL 1, since the power receiving side performscontrol of stopping power supply, it takes a considerable time until thepower supply stops after an unexpected situation occurs. Thus, there isa problem that it is not possible to reduce excessive output or anincrease in magnetic flux leakage for this time period.

An object of the present invention is to provide a power supplyapparatus capable of minimizing excessive output or an increase inmagnetic flux leakage by controlling power supply on the power supplyside when an unexpected situation occurs.

Solution to Problem

A power supply apparatus according to the present invention suppliespower to an external power receiving section in a wireless manner, thepower supply apparatus including: a power supply coil that suppliespower to a power receiving coil of the power receiving section using anelectromagnetic force; and a control section that controls an amount ofpower supply based on an amount of displacement of the power supply coilwhen power is supplied from the power supply coil.

Advantageous Effects of Invention

According to the present invention, it is possible to minimize excessiveoutput or an increase in magnetic flux leakage by controlling the amountof power supply on the power supply side when an unexpected situationoccurs.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a power supplysystem according to an embodiment of the present invention;

FIG. 2 is a flowchart illustrating an operation of a power supplyapparatus according to an embodiment of the present invention; and

FIG. 3 is a diagram illustrating an arrangement of acceleration sensorsaccording to the embodiment of the present invention.

DESCRIPTION OF EMBODIMENT

Hereinafter, an embodiment of the present invention will be described indetail with reference to the accompanying drawings.

(Embodiment)

<Configuration of Power Supply System>

A configuration of power supply system 10 according to an embodiment ofthe present invention will be described using FIG. 1.

Power supply system 10 is mainly composed of power supply apparatus 100,power receiving apparatus 150 and power supply target 160.

Power supply apparatus 100 supplies power to power receiving apparatus150.

By receiving power supply from power supply apparatus 100, powerreceiving apparatus 150 supplies power to power supply target 160.

Power supply target 160 is a load or battery, for example.

Power supply system 10 is used when charging in a wireless manner abattery which is mounted on a vehicle, when charging in a wirelessmanner a battery incorporated in an electric device such as a mobilephone or when supplying power to a load such as a motor to drive theload. When a vehicle-mounted battery is charged in a wireless manner,power supply apparatus 100 is installed on the ground such as a parkingarea and power receiving apparatus 150 is mounted on a vehicle.

<Configuration of Power Supply Apparatus>

A configuration of power supply apparatus 100 according to theembodiment of the present invention will be described using FIG. 1.

Power supply apparatus 100 is mainly composed of power supply 101,inverter 102, power supply coil 103, power-supply-side communicationsection 104, acceleration sensor 105, angular velocity sensor 106, andpower-supply-side control section 107.

Power supply 101 supplies power to inverter 102.

Inverter 102 converts DC power supplied from power supply 101 to ACpower under the control of power-supply-side control section 107 andsupplies a predetermined amount of AC power to power supply coil 103.Inverter 102 changes the amount of power supplied to power supply coil103 under the control of power-supply-side control section 107.

Upon receiving power supply from inverter 102, power supply coil 103supplies power to power receiving coil 154. Power supply coil 103 andpower receiving coil 154 are planar spiral coils, for example. Powersupply coil 103 supplies power in the amount of power corresponding tothe amount of power supplied from inverter 102. When supplying power,power supply coil 103 is magnetically coupled with power receiving coil154 while facing power receiving coil 154. Power supply coil 103supplies power to power receiving coil 154 according to, for example, anelectromagnetic induction scheme or magnetic resonance scheme using anelectromagnetic force.

Power-supply-side communication section 104 exchanges informationrelating to power supply start or power supply stop withpower-receiving-side communication section 153 under the control ofpower-supply-side control section 107 through wireless communication.Power-supply-side communication section 104 outputs, on the basis of theexchanged information, to power-supply-side control section 107, asignal indicating that power supply is possible or a signal indicatingthat power supply is not possible.

Acceleration sensor 105 is installed in the periphery of power supplycoil 103. Acceleration sensor 105 detects acceleration of power supplyapparatus 100 and outputs the detection value to power-supply-sidecontrol section 107. By detecting the acceleration of power supplyapparatus 100, acceleration sensor 105 detects acceleration of powersupply coil 103. Acceleration sensor 105 is, for example, a triaxialacceleration sensor that can detect acceleration in three mutuallyorthogonal axial directions.

Angular velocity sensor 106 is installed in the periphery of powersupply coil 103. Angular velocity sensor 106 detects an angular velocityof power supply apparatus 100 and outputs the detection value topower-supply-side control section 107. By detecting the angular velocityof power supply apparatus 100, angular velocity sensor 106 detects anangular velocity of power supply coil 103. Angular velocity sensor 106is, for example, a triaxial angular velocity sensor that can detectangular velocities in three mutually orthogonal axial directions.

Upon receiving a signal indicating that power supply is possible frompower-supply-side communication section 104, power-supply-side controlsection 107 controls inverter 102 so as to supply the power of powersupply 101 to power supply coil 103. Upon receiving a signal indicatingthat power supply is not possible from power-supply-side communicationsection 104, power-supply-side control section 107 controls inverter 102so as to stop the power supply from power supply 101 to power supplycoil 103.

During power supply during which power is being supplied from powersupply 101 to power supply coil 103, power-supply-side control section107 accumulates detection values indicating the displacement of powersupply coil 103 received from acceleration sensor 105 or angularvelocity sensor 106 for a predetermined time, and thereby calculates theamount of displacement of power supply coil 103. Power-supply-sidecontrol section 107 controls inverter 102 based on the calculated amountof displacement, and thereby controls the amount of power supply.

More specifically, when the amount of displacement is equal to orgreater than a threshold, power-supply-side control section 107 controlsinverter 102 so that the amount of power supplied to power supply coil103 becomes small compared to the case where the amount of displacementis smaller than the threshold. Furthermore, when the amount ofdisplacement is equal to or greater than the threshold,power-supply-side control section 107 controls inverter 102 so as tostop power supply to power supply coil 103. Furthermore, when the amountof displacement is equal to or greater than threshold A but less thanthreshold B (threshold B>threshold A), power-supply-side control section107 controls inverter 102 so that the amount of power supplied to powersupply coil 103 is reduced compared to the case where the amount ofdisplacement is less than threshold A, and power-supply-side controlsection 107 controls inverter 102 so as to stop the power supply topower supply coil 103 when the amount of displacement is equal to orgreater than threshold B. Here, stopping power supply means reducing theamount of power supplied from power supply coil 103 to “zero”.

Note that, for example, when charging system 10 is mounted on a vehicle,an acceleration sensor and an angular velocity sensor provided for a carnavigation apparatus may be also used as acceleration sensor 105 andangular velocity sensor 106.

<Configuration of Power Receiving Apparatus>

A configuration of power receiving apparatus 150 according to theembodiment of the present invention will be described using FIG. 1.

Power receiving apparatus 150 is mainly composed of power-receiving-sidecontrol section 151, inverter 152, power-receiving-side communicationsection 153 and power receiving coil 154.

Upon receiving a signal indicating that power supply is possible frompower-receiving-side communication section 153, power-receiving-sidecontrol section 151 controls inverter 152 so as to supply the powerreceived by power receiving coil 154 to power supply target 160. Uponreceiving a signal indicating that power supply is not possible frompower-receiving-side communication section 153, power-receiving-sidecontrol section 151 controls inverter 152 so as to stop supplying thepower received by power receiving coil 154 to power supply target 160.

Inverter 152 converts AC power supplied from power receiving coil 154 toDC power under the control of power-receiving-side control section 151and supplies the DC power to power supply target 160. Note that, arectifier using a diode, for example, may also be used to convert AC toDC instead of inverter 152.

Power-receiving-side communication section 153 exchanges informationrelating to power supply start or power supply stop withpower-supply-side communication section 104 through wirelesscommunication under the control of power-receiving-side control section151. Based on the exchanged information, power-receiving-sidecommunication section 153 outputs a signal indicating that power supplyis possible or a signal indicating that power supply is not possible topower-receiving-side control section 151.

Power receiving coil 154 receives power from power supply coil 103.

<Operation of Power Supply Apparatus>

An operation of power supply apparatus 100 according to the embodimentof the present invention will be described using FIG. 2.

First, power supply apparatus 100 determines whether or not there is apower-supply-start instruction (step ST201).

When there is no power-supply-start instruction (step ST201: No), powersupply apparatus 100 repeats the process in step ST201.

On the other hand, in power supply apparatus 100, when there is apower-supply-start instruction (step ST201: Yes), power-supply-sidecontrol section 107 determines whether or not power supply is possibleby receiving a signal indicating that power supply is possible (stepST202). Upon receiving a signal indicating that power supply ispossible, power-supply-side control section 107 determines that powersupply is possible and upon receiving a signal indicating that powersupply is not possible, power-supply-side control section 107 determinesthat power supply is not possible.

When power supply is not possible (step ST202: No), power supplyapparatus 100 ends the process.

On the other hand, when power supply is possible (step ST202: Yes),power supply apparatus 100 sets a power supply condition (step ST203)and starts power supply (step ST204).

Next, in power supply apparatus 100, power-supply-side control section107 determines whether or not a displacement of power supply coil 103has been detected (step ST205). Upon receiving a detection value fromacceleration sensor 105 or angular velocity sensor 106,power-supply-side control section 107 determines that a displacement hasbeen detected. Here, the term “displacement” refers to a positionalchange.

In power supply apparatus 100, when no displacement of power supply coil103 has been detected (step ST205: No), power-supply-side controlsection 107 determines whether or not an overcurrent or overvoltage hasoccurred (step ST206).

On the other hand, in power supply apparatus 100, when a displacement ofpower supply coil 103 has been detected (step ST205: Yes),power-supply-side control section 107 determines whether or not theamount of displacement is equal to or greater than threshold A (stepST207).

When the amount of displacement is less than threshold A (step ST207:No), power supply apparatus 100 proceeds to a process in step ST206.

On the other hand, in power supply apparatus 100, when the amount ofdisplacement is equal to or greater than threshold A (step ST207: Yes),power-supply-side control section 107 determines whether or not theamount of displacement is equal to or greater than threshold B(threshold B>threshold A) (step ST208).

In power supply apparatus 100, when the amount of displacement is equalto or greater than threshold B (step ST208: Yes), power-supply-sidecontrol section 107 performs control so as to stop power supply frompower supply coil 103 (step ST209) and ends the process.

On the other hand, in power supply apparatus 100, when the amount ofdisplacement is less than threshold B (step ST208: No),power-supply-side control section 107 performs control so that theamount of power supply from power supply coil 103 is reduced compared tothe case where the amount of displacement is equal to or greater thanthreshold B (step ST210), and then proceeds to step ST206.

In step ST206 when an overcurrent or overvoltage has occurred (stepST206: Yes), power supply apparatus 100 performs control so as to stoppower supply from power supply coil 103 (step ST209) and ends theprocess.

On the other hand, when no overcurrent or overvoltage has occurred instep ST206 (step ST206: No), power supply apparatus 100 determineswhether or not a power-supply-stop instruction has been received fromthe outside (step ST211).

When a power-supply-stop instruction has been received from the outside(step ST211: Yes), power supply apparatus 100 performs control so as tostop power supply from power supply coil 103 (step ST209), and ends theprocess.

On the other hand, when no power-supply-stop instruction has beenreceived (step ST211: No), power supply apparatus 100 returns to theprocess in step ST205.

Note that in FIG. 2, when the amount of displacement is equal to orgreater than threshold B, the power supply is stopped to end theprocess, but power supply may be resumed when the amount of displacementis less than threshold B after stopping the power supply.

<Arrangement of Acceleration Sensors>

An arrangement of acceleration sensors 105 according to the embodimentof the present invention will be described using FIG. 3.

FIG. 3 illustrates an arrangement of acceleration sensors 105 as seenfrom a direction in which power supply coil 103 and power receiving coil154 face each other (direction shown by arrow S1 in FIG. 1).

For example, in the case where one acceleration sensor 105 detects adisplacement of power supply coil 103, in a rotation around accelerationsensor 105, the position of power supply coil 103 with respect to powerreceiving coil 154 is shifted regardless of acceleration “zero” and thestate of coupling between power supply coil 103 and power receiving coil154 changes.

In order to solve the above problem, three acceleration sensors 105 a,105 b and 105 c are arranged in the manner shown in FIG. 3. That is,acceleration sensors 105 a, 105 b and 105 c are arranged at vertices oftriangle E1 respectively. Thus, power supply apparatus 100 can detect adisplacement in all directions of power supply coil 103.

Note that instead of arranging three acceleration sensors 105 a, 105 band 105 c as shown in FIG. 3, power supply apparatus 100 can detect thedisplacement of power supply coil 103 in all directions using oneacceleration sensor 105 a capable of detecting acceleration in triaxialdirections and one angular velocity sensor 106 capable of detectingangular velocities in triaxial directions.

Although three acceleration sensors 105 a, 105 b and 105 c are arrangedat vertices of triangle E1 respectively, the acceleration sensors mayalso be arranged at vertices of a polygon other than a triangle unless aplurality of acceleration sensors are arranged on a single straightline. The acceleration sensors are arranged at vertices of a polygonbecause when a plurality of acceleration sensors are arranged on asingle straight line, if a displacement that rotates around thisstraight line as the axis of rotation occurs, it is no longer possibleto detect the displacement.

Moreover, when acceleration sensor 105 is arranged as shown in FIG. 3,angular velocity sensor 106 may be omitted.

As long as displacements and rotations in triaxial directions of powersupply coil 103 can be detected, any given number of accelerationsensors 105 and angular velocity sensors 106 can be arranged in anygiven arrangement.

When a mechanical restricting section for restricting a displacement ina specific one or multiple directions is provided separately, and adisplacement in a direction in which the section for restricting thedisplacement thereby need not be detected, or when the influence of thedisplacement on the power supply is sufficiently small, the number ofaxes of acceleration sensors 105 and angular velocity sensor 106 may befewer than three or one of acceleration sensor 105 and angular velocitysensor 106 may be omitted.

<Threshold to be Compared with Amount of Displacement of Power SupplyCoil>

A threshold with which the amount of displacement of power supply coil103 according to the embodiment of the present invention is comparedwill be described.

When a mechanical restricting section for restricting a displacement ofpower supply coil 103 is provided or a mechanical restricting sectionfor restricting a relative displacement between power supply coil 103and power receiving coil 154 is provided separately, it is possible tomake a threshold to be compared with the amount of displacement of powersupply coil 103 with respect to the direction in which the restrictingsection is provided greater than a threshold to be compared with theamount of displacement of power supply coil 103 with respect to anotherdirection.

Examples of the mechanical restricting section include a member thatcomes into contact with power supply apparatus 100 when power supplyapparatus 100 displaces to prevent further a displacement of powersupply apparatus 100 or a member that restricts a relative displacementbetween power supply coil 103 and power receiving coil 154.

Thus, when power supply coil 103 displaces in the direction in which therestricting section is provided, or when the relative displacementbetween power supply coil 103 and power receiving coil 154 by provisionof the restricting section is small, and in a situation in whichcontinuation of power supply poses no problem, it is possible to preventa reduction in the amount of power supply or the power supply from beingstopped.

<Effects of Present Embodiment>

The present embodiment controls power supply on the power supply sidewhen an unexpected situation occurs and can thereby minimize excessiveoutput or an increase in magnetic flux leakage.

The present embodiment arranges the acceleration sensors at vertices ofa polygon respectively, and can thereby detect a displacement of powersupply coil 103 in all detections.

The present embodiment uses triaxial gyroscopes as angular velocitysensors 106, and can thereby reduce the number of sensors for detectinga displacement of power supply coil 103 and reduce the manufacturingcost.

The present embodiment reduces the amount of power supply when theamount of displacement of power supply coil 103 is equal to or greaterthan threshold A but less than threshold B, and can thereby reduce thefrequency with which power supply is stopped compared to a case wherepower supply is immediately stopped.

<Variations of Present Embodiment>

The present embodiment reduces the amount of power supply when theamount of displacement of power supply coil 103 is equal to or greaterthan threshold A but less than threshold B, but the power supply may beimmediately stopped when the amount of displacement of power supply coil103 is equal to or greater than threshold A.

The present embodiment detects a displacement of power supply coil 103using acceleration sensor 105 or angular velocity sensor 106, but anygiven sensor can be used if this can detect a displacement of powersupply coil 103.

In the present embodiment, the installation location of the power supplyapparatus is not limited to the ground but may be a mobile unit such asan automobile, railway vehicle, aircraft, ship or playground equipment.In this case, for example, the power receiving side may be a smallelectronic device such as a portable device.

In the present embodiment, the power supply coil and the power receivingcoil are assumed to be planar spiral coils, but any coil other than thespiral coil may be used if this is a coil which can transmit and/orreceive power, and a solenoid coil may be used, for example.

The disclosure of Japanese Patent Application No. 2013-060080, filed onMar. 22, 2013, including the specification, drawings and abstract isincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The present invention is suitable for use in a power supply apparatusthat supplies power to an external power receiving section using anelectromagnetic force in a wireless manner.

REFERENCE SIGNS LIST

-   10 Power supply system-   100 Power supply apparatus-   101 Power supply-   102 Inverter-   103 Power supply coil-   104 Power-supply-side communication section-   105 Acceleration sensor-   106 Angular velocity sensor-   107 Power-supply-side control section-   150 Power receiving apparatus-   151 Power-receiving-side control section-   152 Inverter-   153 Power-receiving-side communication section-   154 Power receiving coil-   160 Power supply target

The invention claimed is:
 1. A power supply apparatus comprising: apower supply coil that supplies power to an external power receivingcoil in a wireless manner using an electromagnetic force; and acontroller that controls an amount of power supply that changes amagnetic coupling between the power supply coil and the power receivingcoil based on an amount of displacement of a position of the powersupply coil with respect to the power receiving coil when vibration isadded to the power supply apparatus when power is supplied from thepower supply coil, wherein, when the amount of displacement during powersupplying from the power supply coil is equal to or greater than athreshold, the controller reduces the amount of power supply thatchanges the magnetic coupling between the power supply coil and thepower receiving coil, the amount of power supply being lower than a casewhere the amount of displacement during power supplying from the powersupply coil is less than the threshold.
 2. The power supply apparatusaccording to claim 1, further comprising a sensor that detects adisplacement of the power supply coil, wherein the controller calculatesthe amount of the displacement from an accumulation of displacementsdetected by the sensor for a predetermined time.
 3. The power supplyapparatus according to claim 2, wherein the sensor detects anacceleration of the power supply coil as the displacement.
 4. The powersupply apparatus according to claim 2, wherein the sensor detects anangular velocity of the power supply coil as the displacement.
 5. Thepower supply apparatus according to claim 1, wherein the displacement iscaused by vibration added to the power supply side during power supplydue to an earthquake.